Enable gosec linter for golangci-lint

`gosec` linter is able to identify issues described in #6584

e.g.

$ git revert 54e95e6b88
[gosec dfc8ca1ec] Revert "fix Implicit memory aliasing in for loop"
 2 files changed, 2 deletions(-)

$ make check
+ proto-fmt
+ check
GOGC=75 golangci-lint run
containerstore.go:192:54: G601: Implicit memory aliasing in for loop. (gosec)
		containers = append(containers, containerFromProto(&container))
		                                                   ^
image_store.go:132:42: G601: Implicit memory aliasing in for loop. (gosec)
		images = append(images, imageFromProto(&image))
		                                       ^
make: *** [check] Error 1

I also disabled following two settings which prevent the linter to show a complete list of issues.

* max-issues-per-linter (default 50)
* max-same-issues (default 3)

Furthermore enabling gosec revealed many other issues. For now I blacklisted the ones except G601.

Will create separate tasks to address them one by one moving next.

Signed-off-by: Henry Wang <henwang@amazon.com>

metadata/boltutil/helpers.go

@@ -162,6 +162,7 @@ func WriteExtensions(bkt *bolt.Bucket, extensions map[string]types.Any) error {
 	}
 
 	for name, ext := range extensions {
+		ext := ext
 		p, err := proto.Marshal(&ext)
 		if err != nil {
 			return err